1. Field of the Invention
The present invention relates to an apparatus for replacing gas in a storage container and a method for replacing gas therewith. The apparatus for replacing gas in a storage container replaces gas in a storage container with an inert gas and the like while accommodating a material such as semiconductor wafers for which prevention of foreign matter adhesion is required, and the apparatus for replacing gas in a storage container also cleans surfaces of the semiconductor wafers and the like accommodated in the storage container.
2. Description of the Related Art
While a diameter of the semiconductor wafer is increased, miniaturization of a process pattern formed in the semiconductor wafer is rapidly in progress. Therefore, in the semiconductor wafer, technical requirements for the prevention of contamination and the cleanness of the surface are increased more and more.
In order to respond to such requirements, in the semiconductor wafer storage container for accommodating and storing a semiconductor wafer, there is developed the technology in which surface degradation caused by adsorption of impurity elements or moisture in the storage container is prevented while the semiconductor wafer surfaces are kept clean.
Recently, the semiconductor wafer storage container has a structure in which a lid of the storage container can mechanically be opened and closed so that the semiconductor wafers are automatically loaded and unloaded in an unmanned process room having a high cleanness level.
Further, use of the semiconductor wafer storage container, in which corrosion of the electrodes formed in the semiconductor wafer surface can be prevented by filling the inside of the storage container with the inert gas, is also becoming widespread. For example, Japanese Patent Application Laid-Open (JP-A) No. 5-74921 (pp 4 to 5, FIG. 2) discloses the technology concerning gas replacement in the storage container. In the gas replacement disclosed in JP-A No. 5-74921, an airtight maintaining type coupler which can be connected to a gas setting device is mounted on the semiconductor wafer storage container, and the storage container is filled with the dry and clean gas such as air, a nitrogen gas, and the inert gas through the airtight maintaining type coupler.
However, in the conventional gas replacing apparatus and method disclosed in JP-A No. 5-74921, because the gas replacement is performed after the air in the storage container is evacuated, it is necessary that ultimate vacuum in the storage container becomes sufficiently high after the evacuation in order to increase gas purity after the gas replacement. Therefore, the plastic storage container usually used has a problem of pressure-resistance intensity.
When the vacuum of the storage container is reduced before the gas replacement, in order to perform the high-purity gas replacement in an airtight manner, there is the problem that a sufficiently long time is required for the gas replacement.
In order to remove the moisture and impurities adsorbed onto the semiconductor wafer, it is necessary that the inside of the storage container is heated with a heating device provided in the storage container. Therefore, there are problems that the plastic storage container cannot be used and a treatment-time is lengthened.
In the conventional gas replacing apparatus and method disclosed in JP-A No. 5-74921, it is necessary to use the semiconductor wafer storage container in which a replacement gas inlet is made. Therefore, for the generally used semiconductor wafer storage container with no replacement gas inlet, there is the problem that the gas replacement cannot be performed.